This invention refers to a vehicle gear-change in which the lever transmission to the corresponding gear and gear-change selection cables is a lineal transmission movement thus allowing the force of the actual lever to be fully availed of.
The purpose of the invention is to a provide a gear-change for vehicles in which the movement of the selection cables is linearly executed, which allows a more compact mechanism to be obtained, a lighter lever and the use of plastic materials.
Conventional gear-changes normally have a structure based on an activating lever that acts on two tensile-compression cables, in charge of carrying out the selection of the appropriate gear to be inserted for the speed required.
As is well known, when changing gears the lever is activated by two possible movements, one traverse and the other longitudinal, so that when the lever is transversally activated, it then acts on the gear-change selection cable, or in other words, on the transmission block to be used; whereas when the lever is activated in a longitudinal direction, it then acts on the gear-selection cable that determines which of the transmission block gears previously selected will be connected to the outgoing axle, and therefore the speed to be introduced.
Also, the fact is known that in gear-changes the activating lever finishes in a swivel joint that is located in a casing for securing it to the vehicle bodywork, a swivel joint that allows traverse and longitudinal movements of the lever previously alluded to.
Furthermore in conventional gear-changes, from the swivel joint referred to an arm projects downwards, and sometimes upwards, that at one end is attached to the gear-selection activating cable, so that forward or backward movement of the lever will cause the traction or compression of the cable and therefore connection with one of the gears of the corresponding transmission block.
Also of conventional use in the gear-changes is the arrangement that the swivel joint is linked to a traverse arm that acts on a articulated rod that, at its other end, is joined to gear-change selection cable, so that the traverse movement of the lever causes the articulated rod to tilt, which will then stretch or compress the activating cable that will select the corresponding transmission block.
The gear-change systems of the type referred to present the complication that the movement of the lever on the activating cables is circular in nature, and therefore the force applied onto the lever isn""t completely transmitted in the direction of the cable, but rather it will divide into a tangential force (in the direction of the cable) and into a radial force (perpendicular to the cable), or, in other words, all of the force applied to the lever won""t be fully transmitted.
Also, by using a swivel joint for the transmission of movement, the ends of the articulated rods, that act on the cables, follow circular paths, because of which the approach to the cable ends is not always made at the same angle, requiring pivot joints or parts that compensate for this effect and that logically complicate the mechanism; the movement kinematic chain being equally complicated on requiring the use of the articulated rod to allow traverse movement of the lever.
The vehicle gear-change that is proposed has been envisaged to fully resolve that difficulty, using a simple and efficient solution, based on a lineal movement concept, using for this purpose a lineal movement slide block or slide instead of the classic articulated rod of the kinematic chains used in conventional gear changes.
More specifically, the gear-change that is the subject of the invention includes a cam that is mounted inside a casing with respect to which it can tilt, said cam being linked to the corresponding activating lever, which is hinged between lugs extending towards the cam and linked at its lower end to a slide or lineal slide block to which the gear selection cable is linked, while another slide or slide block, also with the possibility of lineal movement, is linked to the gear change selection cable, this second slide block or slide having a protrusion or side protuberance that fits into a slanting aperture placed in the side wall of the cam, the slanting acting as a transmission contour so that in the traverse action of the lever the rotation or tilting of the lever towards one side or another of the cam takes place and with it the forward or backward movement of the aforementioned slide or slide block, to which the gear-selection cable is linked, producing its compression or traction.
The forwards or backwards movement of the activating lever will cause it to be tilted with respect to the cam connection lugs, in such a way that the lower end of the aforementioned lever will push the slide block, that is linked to the gear-selection cable, forwards or backwards, producing its compression or traction.
By means of this extremely simple solution a lineal movement transmission is obtained, with which full advantage is taken of the forces transmitted to the gear lever.
A simplification of the structure is also achieved, by disposing of the articulated rod of the conventional gear-changes, permitting a simpler assembly of selection cables, since the slide or slide blocks and the cables are aligned and their movements are always lengthways.
Therefore, a notably more compact mechanism than the conventional ones can be obtained, as well as it being possible to fabricate it completely from plastic, thus eliminating the metallic materials that are normally used in this type of mechanism, all of which will have repercussions in the vehicle since, on one hand, less space will be needed to install the mechanism, and on the other, the weight will be less, with the consequent advantages arising from this.